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14th December 2010, 10:39am
Award-winning study suggests low-carbohydrate diet could cut risks of killer diseases
Chips are a high-GI food Nutritionists at the University of Lincoln have won an award for their research which suggests that a low-carbohydrate diet could be better at cutting the risks of developing cardiovascular diseases than a conventional low-fat diet.

Researchers found that overweight women who followed a low-calorie, low-carbohydrate diet for eight weeks not only saw a drop in their weight, body mass index (BMI) and blood pressure, but also showed a significant drop in bloodstream enzymes and compounds linked to heart disease, stroke and liver damage. Women who followed a more conventional low-fat diet over the same period experienced a similar reduction in weight, BMI and blood pressure – but not the same bloodstream changes.

The findings appear to support previous studies which suggest that a diet low in carbohydrate and Glycemic Index (also called a low-GI diet) could have added health benefits.

Foods which are classed as ‘low-GI’ release glucose more gradually as they break down on digestion. They include muesli, brown rice and wholemeal bread. By contrast, high-GI foods release glucose more quickly, producing a ‘sugar-rush’ sensation. They include foods like short grain white rice, chips and mashed potato.

The researchers at Lincoln recruited 40 female volunteers to take part in their study. All were classed as overweight or obese with a BMI over 25. The participants were split into two groups of 20, one on a low fat diet, the other on a low-carbohydrate (low-GI) diet. Both groups’ diets provided a calorie intake of around 1,200kcal per day. The volunteers were asked to follow the diets for eight weeks, completing interviews, health checks and diet diaries at regular points. Blood tests were taken at the start, half-way point and end of the study period.

Both groups showed significant reductions in weight and BMI over the eight weeks. Blood pressure also fell across both groups. However, in blood tests the low-GI diet group showed chemical changes in two areas not seen in the low-fat group. The first change was a reduction in serum triglyceride concentration. High levels of triglycerides in the bloodstream are linked to build-up of cholesterol in the blood vessels which increase the risks of cardiovascular disease such as heart attack and stroke. The second change was a significant reduction in alanine aminotransferase (ALT) concentration. This measure is commonly used to assess liver health. High ALT levels are a recognised indicator of liver damage.

The research was conducted by Dr Anne Morris, Dr Shamusi Fagbemi and Dr Tanefa Apekey from the University of Lincoln’s School of Natural and Applied Sciences, alongside Graham J. Griffiths, from the clinical pathology department at Lincoln County Hospital.

Their study ‘Effects of low-fat and low-GI diets on health’, published in the journal ‘Nutrition & Food Science’, was selected as a Highly Commended Paper at the Emerald Literati Network Awards for Excellence 2010. It means the study was one of the most highly rated papers received by editorial teams across all of Emerald’s academic journals. The paper was written from Dr Apekey's PhD research at Lincoln for which Dr Morris was first supervisor and Dr Fagbemi second supervisor.

Dr Apekey, now a research assistant at the University of Leeds, said: "Conventional wisdom and current government advice for people wanting to lose weight is to reduce their daily calorie count through a low-fat diet and to exercise regularly. In this study we wanted to compare the health benefits of low-fat and low-GI diets. Our findings indicate that while the effects on weight, BMI and blood pressure were largely the same, the low-GI diet appeared to produce other effects which could make it more effective at reducing the risks of cardiovascular disease and could also improve liver function."

Dr Morris said: "We were extremely proud to receive this award for our research paper, particularly as it was selected by an editorial panel comprised of eminent academics. For our work to be considered one of the best papers published in ‘Nutrition and Food Science’ in 2009 is a tremendous accolade for the School of Natural and Applied Sciences here at Lincoln. This research has built on previous findings on the potential health benefits of low-GI diets and opened interesting new avenues for further study."

‘Effects of low-fat and low-GI diets on health’ by Tanefa A. Apekey, Anne J. E. Morris, Shamusi Fagbemi and Graham J. Griffiths was published in the journal ‘Nutrition & Food Science’, Vol. 39 No. 6, 2009 pp. 663-675 copyright Emerald Group Publishing Limited.

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